The present invention relates to an electric power steering apparatus using a motor rotational force as auxiliary power.
A conventional power steering apparatus using a motor rotational force as an auxiliary power source is described in Japanese Utility Model Publication No. 59-17759. In this apparatus, a motor is driven by a bridge circuit consisting of switching elements, and a drive circuit determines which one of pairs of opposite sides of the bridge circuit is driven. However, in this conventional apparatus, when motor power is increased, operation thereof becomes unstable.